ai-chatbot/lib/video-canvas/storyboard-composition.ts

export type VideoCanvasStoryboardCompositionClip = {
  durationSeconds: number;
  id: string;
  inPointSeconds: number;
  mediaUrl: string;
  nodeId: string;
  outPointSeconds: number;
  speed: number;
  title: string;
  transition: VideoCanvasStoryboardCompositionTransition | null;
};

export type VideoCanvasStoryboardCompositionSubtitle = {
  endSeconds: number;
  id: string;
  startSeconds: number;
  text: string;
};

export type VideoCanvasStoryboardCompositionTransition =
  | "fade"
  | "fade-black"
  | "fade-white";

export type VideoCanvasStoryboardCompositionProject = {
  clips: VideoCanvasStoryboardCompositionClip[];
  subtitles: VideoCanvasStoryboardCompositionSubtitle[];
};

export const EMPTY_VIDEO_CANVAS_STORYBOARD_COMPOSITION: VideoCanvasStoryboardCompositionProject = {
  clips: [],
  subtitles: [],
};

const clamp = (value: number, min: number, max: number) =>
  Math.min(Math.max(value, min), max);

const asString = (value: unknown) =>
  typeof value === "string" ? value.trim() : "";

const asFiniteNumber = (value: unknown, fallback: number) => {
  const number = Number(value);
  return Number.isFinite(number) ? number : fallback;
};

export function normalizeVideoCanvasStoryboardComposition(
  value: unknown,
): VideoCanvasStoryboardCompositionProject {
  if (!value || typeof value !== "object" || Array.isArray(value)) {
    return structuredClone(EMPTY_VIDEO_CANVAS_STORYBOARD_COMPOSITION);
  }

  const source = value as Record<string, unknown>;
  const clips = Array.isArray(source.clips)
    ? source.clips.flatMap((candidate, index) => {
        if (!candidate || typeof candidate !== "object" || Array.isArray(candidate)) {
          return [];
        }
        const clip = candidate as Record<string, unknown>;
        const nodeId = asString(clip.nodeId);
        const mediaUrl = asString(clip.mediaUrl);
        if (!(nodeId && mediaUrl)) return [];

        const durationSeconds = Math.max(
          0.1,
          asFiniteNumber(clip.durationSeconds, 5),
        );
        const inPointSeconds = clamp(
          asFiniteNumber(clip.inPointSeconds, 0),
          0,
          Math.max(0, durationSeconds - 0.1),
        );
        const outPointSeconds = clamp(
          asFiniteNumber(clip.outPointSeconds, durationSeconds),
          inPointSeconds + 0.1,
          durationSeconds,
        );
        const transition = asString(clip.transition);

        return [{
          durationSeconds,
          id: asString(clip.id) || `${nodeId}-${index + 1}`,
          inPointSeconds,
          mediaUrl,
          nodeId,
          outPointSeconds,
          speed: clamp(asFiniteNumber(clip.speed, 1), 0.25, 4),
          title: asString(clip.title) || "视频片段",
          transition:
            transition === "fade" ||
            transition === "fade-black" ||
            transition === "fade-white"
              ? transition
              : null,
        } satisfies VideoCanvasStoryboardCompositionClip];
      })
    : [];

  const subtitles = Array.isArray(source.subtitles)
    ? source.subtitles.flatMap((candidate, index) => {
        if (!candidate || typeof candidate !== "object" || Array.isArray(candidate)) {
          return [];
        }
        const subtitle = candidate as Record<string, unknown>;
        const startSeconds = Math.max(
          0,
          asFiniteNumber(subtitle.startSeconds, 0),
        );
        const endSeconds = Math.max(
          startSeconds + 0.1,
          asFiniteNumber(subtitle.endSeconds, startSeconds + 2),
        );
        return [{
          endSeconds,
          id: asString(subtitle.id) || `subtitle-${index + 1}`,
          startSeconds,
          text: asString(subtitle.text) || "新建字幕",
        } satisfies VideoCanvasStoryboardCompositionSubtitle];
      })
    : [];

  return { clips, subtitles };
}

export function getVideoCanvasCompositionClipDuration(
  clip: VideoCanvasStoryboardCompositionClip,
) {
  return Math.max(0.1, clip.outPointSeconds - clip.inPointSeconds) / clip.speed;
}

export function getVideoCanvasCompositionDuration(
  project: VideoCanvasStoryboardCompositionProject,
) {
  return project.clips.reduce(
    (total, clip) => total + getVideoCanvasCompositionClipDuration(clip),
    0,
  );
}

export function getVideoCanvasCompositionClipStart(
  project: VideoCanvasStoryboardCompositionProject,
  clipId: string,
) {
  let start = 0;
  for (const clip of project.clips) {
    if (clip.id === clipId) return start;
    start += getVideoCanvasCompositionClipDuration(clip);
  }
  return null;
}

export function createVideoCanvasCompositionClip({
  durationSeconds,
  existingIds,
  mediaUrl,
  nodeId,
  title,
}: {
  durationSeconds: number;
  existingIds: string[];
  mediaUrl: string;
  nodeId: string;
  title: string;
}): VideoCanvasStoryboardCompositionClip {
  const normalizedDuration = Math.max(0.1, durationSeconds || 5);
  const baseId = `${nodeId}-clip`;
  let suffix = 1;
  let id = `${baseId}-${suffix}`;
  while (existingIds.includes(id)) {
    suffix += 1;
    id = `${baseId}-${suffix}`;
  }
  return {
    durationSeconds: normalizedDuration,
    id,
    inPointSeconds: 0,
    mediaUrl,
    nodeId,
    outPointSeconds: normalizedDuration,
    speed: 1,
    title: title.trim() || "视频片段",
    transition: null,
  };
}

export function splitVideoCanvasCompositionClip(
  project: VideoCanvasStoryboardCompositionProject,
  clipId: string,
  playheadSeconds: number,
): VideoCanvasStoryboardCompositionProject {
  const clipIndex = project.clips.findIndex((clip) => clip.id === clipId);
  const clipStart = getVideoCanvasCompositionClipStart(project, clipId);
  if (clipIndex < 0 || clipStart === null) return project;

  const clip = project.clips[clipIndex];
  const relativeTimelineSeconds = playheadSeconds - clipStart;
  const sourceSplitSeconds =
    clip.inPointSeconds + relativeTimelineSeconds * clip.speed;
  if (
    sourceSplitSeconds <= clip.inPointSeconds + 0.1 ||
    sourceSplitSeconds >= clip.outPointSeconds - 0.1
  ) {
    return project;
  }

  const suffix = project.clips.filter((item) => item.id.startsWith(`${clip.id}-split`)).length + 1;
  const left = { ...clip, outPointSeconds: sourceSplitSeconds };
  const right = {
    ...clip,
    id: `${clip.id}-split-${suffix}`,
    inPointSeconds: sourceSplitSeconds,
    transition: null,
  };
  return {
    ...project,
    clips: [
      ...project.clips.slice(0, clipIndex),
      left,
      right,
      ...project.clips.slice(clipIndex + 1),
    ],
  };
}